External board (nRF52820) flashing with different voltage level from nRF52833 DK

[ViktorVarjas]

Dear Support Team!

I'm just about to flash an external board (nRF52820) through P19 where the MCU is powered at 2.3V. I would like to use the nRF52833_DK and the PPK2 to do the flashing and I was wondering what would be the best power source configuration on the DK side to do the flashing? How could I bring the VDD level down to 2.3V on the DK side?

Would powering the DK SoC via P21 (@2.3V) and rest of the DK board via USB and switching the SW10 to "ON" be ok for flashing?

Thank you very much in advance and all the best,

Viktor

[Priyanka]

Hi Viktor, 

Is there any specific reason that you would like to use a lesser voltage level for the same?

Best Regards,

Priyanka

[ViktorVarjas]

Hi Priyanka,

Thank you very much for the reply!

We built a custom PCB for development purpose where the nRF is powered at 2.3V (or 2.0V). The reason is long term consumption and because the nRF specification allows it.

The main question from my side is, if I could get the nRF52833 DK voltage down to 2.3V for successfull flashing as described in the original question:

 "Would powering the DK SoC via P21 (@2.3V) and rest of the DK board via USB and switching the SW10 to "ON" be ok for flashing?"

This way I can measure 2.3V on the DK VDD pins but not sure if the level of the flashing pins are also correct. I just want to make sure before the PCBs arrive not to mess up or destroy anything (was not able to try it on any external board so far).

All the best,

Viktor

[Priyanka]

Hi Viktor, 

I guess it would be much easier if you could lower the entire DK voltage to, say, 2.3V (by just supplying a lower voltage to the external pinheaders). As long as the voltage on the DK and your custom PCB is the same, this should be fine.

-Priyanka

[ViktorVarjas]

Hi Priyanka,

This is exactly what I was asking, if the method I mentioned is the correct way to approach it. I write it down again:

Would powering the DK SoC via P21 (@2.3V) and rest of the DK board via USB and switching the SW10 (follower circuit) to "ON" be ok for flashing?

Viktor

[PaKa]

No, the nRF52833-DK only supports programming 3.0V targets so this will not work. If you need to program targets with other operating voltages you will need to use a SEGGER j-link or similar.

[Priyanka]

Hi Viktor,

Like Paal mentioned, you might need a debugger/programmer with level shifters.

-Priyanka

[ViktorVarjas]

Hi Priyanka and PaKa!

After receiving the custom board I can confirm that the setup proposed in my initial question is working to flash external devices with voltage levels different form the DK (3.0V).

I used 2.0V external board VDD and flashing was without problem with this setup (any VDD between 1.7-3.6 is working!):

The conclusion is that flashing is absolutely possible in the above mentioned setup and no need to buy any external programming device!

It would be very helpful if the information shared here by the technical experts would be valid and not misleading!

All the best,

Viktor